The slope of a line is simply a ratio of the change in y-value to the change in x-value
Change in y = y₂ - y₁
= 12 - (-6) = 18
Change in x = x₂ - x₁
= 6 - 3 = 3
Ratio of change in y to change in x = 18/3 = 6
The slope is 6
9x + 8 = 2
Subtract 8 from both sides:
9x = -6
x = -6/9
Simplify:
x = -2/3